Project Description

In recent years, climate change and environmental deterioration have called significant attention at both the federal and state levels. Reducing greenhouse gas emission and improving energy efficiency have moved to the top priority in most engineering practice. Warm mix asphalt (WMA) technologies have attracted great interests in pavement engineering due to the potential energy savings and environmental benefits. The federal and state DOTs, including NJDOT and NYDOT, have invested much research effort on validating the performance of this innovative technology. The test results have shown that WMA can significantly promote the sustainability of construction without compromising the performance of the mixture.

Although different aggregates and binder types are used, the current specifications have no direction on determining the optimum production and construction temperatures and formulating the best proportion of WMA additives. The mechanism of WMA is to use some additives to modify the rheological behavior of asphalt binder, and thus improve the workability of the mix at lower temperatures. Therefore, it is crucial to understand the rheological behavior of asphalt binder changing with temperatures and proportion of the additives, which will directly affect construction productivity, optimum temperature range, and haul distances of the materials.

This study will evaluate the effect of three kinds of WMA additives on rheological behavior of asphalt binders, namely Advera®, Sasobit®, and Evotherm® as shown in the figure. The viscosity of the binder is measured at different amounts of additives and temperatures. The microstructure of the modified binders is investigated with Scanning Electron Microscope (SEM). A micromechanics?based analysis is conducted to predict the rheological behavior of the modified binders considering the microstructure evolution with temperatures. This study will rationalize the engineering practice of WMA, and provide a novel formulation to derive the production temperature and volume proportion of the WMA additive based on the asphalt binder grade and asphalt types. The success of this work will lead to the significant advances in asphalt pavement construction and maximize the benefits of WMA. In addition, this integrated multiscale research approach will provide a protocol to develop some other types of WMA and promote this green technology.

Publications

• B. Lai, C. Barros, H.M. Yin, 2009, Investigation of rheological behavior of asphalt binder modified by the Advera® additive, /4th Biot Conference on Poromechanics/, p. 487-492, June 8-10, New York, NY.
• H.M. Yin, Opening-mode cracking in asphalt pavements: crack initiation and saturation, /Road Materials and Pavement Design/, (in print).
• H.M. Yin, Fracture saturation and critical thickness in layered materials, /International Journal of Solids and Structures/, (in print).